1. Field of the Invention
The present invention generally relates to an animation producing apparatus for producing animations and, more particularly, is directed to an animation producing apparatus which produces an animation by using a plurality of parameters and a plurality of fundamental shapes.
2. Description of the Prior Art
When an animation of a predetermined character is produced by computer graphics, data of fundamental configuration (i.e. fundamental shape) of the character are inputted and motions of respective parts of the character are given by values of respective parameters. Then, values of all the parameters are gradually changed along a certain time axis, whereby the character can be moved in a desirable fashion. The time axis is what might be called a time line and the unit of the time line is, by way of example, [hour: minute: second: frame number].
FIG. 1 shows a conventional animation producing apparatus which utilizes computer graphics.
In FIG. 1, reference numeral 1 designates a keyboard, 2 a video image input apparatus such as a digitizer or the like, 3 a central processing unit (CPU), 4 a memory such as a random access memory (RAM), magnetic disc apparatus or the like, and 5 a video image display apparatus with a display picture screen 6, such as a cathode ray tube (CRT) Data of a fundamental configuration (i.e. fundamental shape) of a predetermined character are stored in the memory 4 input from the keyboard 1 and the video image input apparatus 2 through the CPU 3. The data of the fundamental shape of the character itself may be generated by an operation of the computer (see U.S. Pat. No. 4,791,581).
If the character is, for example, a man, the man's motions can be expressed by a parameter group P which is formed of three parameters (i.e. a parameter for designating waving of arms, parameter for designating motion of legs and a parameter designating motion of the character in the lateral direction).
More specifically, as shown in FIG. 2, the operator operates the keyboard 1 to set in the memory 4 values P.sub.0, P.sub.1 and P.sub.2 of the parameter group P at timing points t.sub.0, t.sub.1 and t.sub.2 on one time line T. Then, the CPU 3 performs interpolation operations to generate values of parameter group P between timing points t.sub.0 and t.sub.1 and between timing points t.sub.1 and t.sub.2 in units of the frame period, whereby a value of parameter group P.sub.x at, for example, timing point t.sub.x (t.sub.0 &lt;t.sub.x &lt;t.sub.1) becomes an intermediate value between the values P.sub.0 and P.sub.1. Assuming that characters 7.sub.0, 7.sub.1 and 7.sub.2 of shapes designated by the operator are displayed on a display picture screen 6 of the video image display apparatus 5 in response to the values P.sub.0, P.sub.1 and P.sub.2 of the parameter group P, the shape of the character 7.sub.0 is gradually changed to that of the character 7.sub.1 on the display picture screen 6 from timing points t.sub.0 to t.sub.1, and the shape of character 7.sub.1 is gradually changed to that of character 7.sub.2 on the display picture screen 6 from timing points t.sub.1 to t.sub.2.
However, as described above, the operator must simultaneously determine all values of parameters for instructing the motion of arms, the motion of legs and the moving amount of the character in the lateral direction at timing points t.sub.0, t.sub.1 and t.sub.2 which are selected by the operator along one time line T. Accordingly, when the operator wants to change only the motion of the arm of the character after viewing the animations, the operator has to change the parameter for designating the motion of arm along the time line T and must also determine the values of all parameters at each time point one more time. Therefore, the motion of a certain part of the character cannot be changed efficiently.